From 153e5e105e443d24ee3165fddcaf5fe03a91b01d Mon Sep 17 00:00:00 2001
From: Dean Wunder <dean@finao.com.au>
Date: Thu, 12 Jun 2025 11:48:40 +1000
Subject: [PATCH 1/3] collapseWithKeys - Ensure base case of already flat
 collection doesn't result in an exception.

---
 src/Illuminate/Collections/Collection.php | 4 ++++
 tests/Support/SupportCollectionTest.php   | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/src/Illuminate/Collections/Collection.php b/src/Illuminate/Collections/Collection.php
index 95faa17a7121..3d88988b48d5 100644
--- a/src/Illuminate/Collections/Collection.php
+++ b/src/Illuminate/Collections/Collection.php
@@ -165,6 +165,10 @@ public function collapseWithKeys()
             $results[$key] = $values;
         }
 
+        if (!$results) {
+            return $this;
+        }
+
         return new static(array_replace(...$results));
     }
 
diff --git a/tests/Support/SupportCollectionTest.php b/tests/Support/SupportCollectionTest.php
index ac93ab3f2334..a1c799f378d9 100755
--- a/tests/Support/SupportCollectionTest.php
+++ b/tests/Support/SupportCollectionTest.php
@@ -1772,6 +1772,10 @@ public function testCollapseWithKeys($collection)
     {
         $data = new $collection([[1 => 'a'], [3 => 'c'], [2 => 'b'], 'drop']);
         $this->assertEquals([1 => 'a', 3 => 'c', 2 => 'b'], $data->collapseWithKeys()->all());
+
+        // Case with an already flat collection
+        $data = new $collection(['a', 'b', 'c']);
+        $this->assertEquals(['a', 'b', 'c'], $data->collapseWithKeys()->all());
     }
 
     #[DataProvider('collectionClassProvider')]

From 1e33d1a5cf89761c6348d7154f3039ac2064549f Mon Sep 17 00:00:00 2001
From: Dean Wunder <dean@finao.com.au>
Date: Thu, 12 Jun 2025 11:56:47 +1000
Subject: [PATCH 2/3] 12.x  Fix style error

---
 src/Illuminate/Collections/Collection.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Illuminate/Collections/Collection.php b/src/Illuminate/Collections/Collection.php
index 3d88988b48d5..40069cbf1431 100644
--- a/src/Illuminate/Collections/Collection.php
+++ b/src/Illuminate/Collections/Collection.php
@@ -165,7 +165,7 @@ public function collapseWithKeys()
             $results[$key] = $values;
         }
 
-        if (!$results) {
+        if (! $results) {
             return $this;
         }
 

From b3e9026230f18ad208e6a9a7a9178ffb2ac71993 Mon Sep 17 00:00:00 2001
From: Dean Wunder <deanwunder@gmail.com>
Date: Thu, 12 Jun 2025 20:01:17 +1000
Subject: [PATCH 3/3] 12.x  Opting to return empty collection in this case
 instead to ensure functionality of Collection matches LazyCollection

---
 src/Illuminate/Collections/Collection.php | 2 +-
 tests/Support/SupportCollectionTest.php   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Illuminate/Collections/Collection.php b/src/Illuminate/Collections/Collection.php
index 40069cbf1431..becabe47f608 100644
--- a/src/Illuminate/Collections/Collection.php
+++ b/src/Illuminate/Collections/Collection.php
@@ -166,7 +166,7 @@ public function collapseWithKeys()
         }
 
         if (! $results) {
-            return $this;
+            return new static;
         }
 
         return new static(array_replace(...$results));
diff --git a/tests/Support/SupportCollectionTest.php b/tests/Support/SupportCollectionTest.php
index a1c799f378d9..9a5433f3f55f 100755
--- a/tests/Support/SupportCollectionTest.php
+++ b/tests/Support/SupportCollectionTest.php
@@ -1775,7 +1775,7 @@ public function testCollapseWithKeys($collection)
 
         // Case with an already flat collection
         $data = new $collection(['a', 'b', 'c']);
-        $this->assertEquals(['a', 'b', 'c'], $data->collapseWithKeys()->all());
+        $this->assertEquals([], $data->collapseWithKeys()->all());
     }
 
     #[DataProvider('collectionClassProvider')]